Image sensors for video applications may sample a scene with a color filter array (CFA) arranged on a surface of the sensor. A variety of CFA patterns may be used, and a digital signal processor (DSP) may obtain three color values for each photosite. Image processing techniques may be used to obtain high quality, color video images. These image processing techniques may be referred to as “front-end” image processing because it generally precedes image compression or other video coding by a video coding unit. Alternatively, these image processing techniques may be referred to as “post processing” since the processing occurs after images are captured by image sensors.
Image frames of a video sequence generated from an image sensor may be processed by one or more image processing techniques. Examples of image processing techniques include color correction and demosaicing. Image processing may improve visual image quality attributes, such as tone reproduction, color saturation, hue reproduction and sharpness.
A number of video processing and coding techniques have been used for communicating digital video sequences. For example, the Moving Picture Experts Group (MPEG) has developed a number of video coding standards, such as MPEG-1, MPEG-2 and MPEG-4. Other standards include ITU H.263 and ITU H.264.
Some video coding techniques and standards may use graphics and video compression algorithms to compress data. Some compression algorithms may exploit temporal or inter-frame correlation and provide inter-frame compression. Inter-frame compression techniques may exploit data redundancy across frames by converting pixel-based representations of image frames to motion representations.
Some video compression techniques may use similarities within image frames, i.e., spatial or intra-frame correlation, to provide intra-frame compression, in which motion representations within an image frame can be further compressed. Intra-frame compression may use processes for compressing still images, such as discrete cosine transform (DCT) transformation.